Message-ID: <517861E0.7030801@zytor.com>
Date: Wed, 24 Apr 2013 15:51:12 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Minchan Kim <minchan@kernel.org>
CC: Sasha Levin <sasha.levin@oracle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>, Mel Gorman <mgorman@suse.de>,
        Dave Jones <davej@redhat.com>, linux-mm <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: mm: BUG in do_huge_pmd_wp_page
References: <51559150.3040407@oracle.com> <20130410080202.GB21292@blaptop>
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On 04/10/2013 01:02 AM, Minchan Kim wrote:
> 
> When I am looking at the code, I was wonder about the logic of GHZP(aka,
> get_huge_zero_page) reference handling. The logic depends on that page
> allocator never alocate PFN 0.
> 
> Who makes sure it? What happens if allocator allocates PFN 0?
> I don't know all of architecture makes sure it.
> You investigated it for all arches?
> 

This isn't manifest, right?  At least on x86 we should never, ever
allocate PFN 0.

	-hpa


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